Define the TypeScript version you want to use in SharePoint Framework
Since the release of SharePoint Framework 1.8.0, you will gain control over which TypeScript version to run in the build process. Until the release of 1.8.0 version, we were always tight to TypeScript version 2.4.2. There was no way to change this, as it was part of the internal SPFx build engine, but this has changed.
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